A wireless device, such as a base station, in a wireless communication system includes a filter having a resonator.
PTL 1 discloses a filter using a dielectric resonance element which stably operates even when a temperature change occurs. In PTL 1, when the dielectric resonance element is stretched in the height direction thereof due to a change in ambient temperature, a mechanism for absorbing the stretched portion is provided at a metallic cover that houses the dielectric resonance element.